U.S. patent number 10,020,259 [Application Number 15/463,617] was granted by the patent office on 2018-07-10 for copper etching integration scheme.
This patent grant is currently assigned to Taiwan Semiconductor Manufacturing Co., Ltd.. The grantee listed for this patent is Taiwan Semiconductor Manufacturing Co., Ltd.. Invention is credited to Tien-I Bao, Chung-Ju Lee, Hsiang-Huan Lee, Chih-Wei Lu.
United States Patent |
10,020,259 |
Lu , et al. |
July 10, 2018 |
Copper etching integration scheme
Abstract
The present disclosure relates to a method for forming an
interconnect structure. In some embodiments, the method may be
performed by forming an opening within a sacrificial layer. The
sacrificial layer is over a substrate. A conductive material is
formed within the opening and over the sacrificial layer. The
conductive material within the opening defines a conductive body.
The conductive material is patterned to define a conductive
projection extending outward from the conductive body. The
sacrificial layer is removed and a dielectric material is formed
surrounding the conductive body and the conductive projection.
Inventors: |
Lu; Chih-Wei (Hsinchu,
TW), Lee; Chung-Ju (Hsinchu, TW), Lee;
Hsiang-Huan (Jhudong Township, TW), Bao; Tien-I
(Taoyuan, TW) |
Applicant: |
Name |
City |
State |
Country |
Type |
Taiwan Semiconductor Manufacturing Co., Ltd. |
Hsin-Chu |
N/A |
TW |
|
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Assignee: |
Taiwan Semiconductor Manufacturing
Co., Ltd. (Hsin-Chu, TW)
|
Family
ID: |
51164556 |
Appl.
No.: |
15/463,617 |
Filed: |
March 20, 2017 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20170194258 A1 |
Jul 6, 2017 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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15153967 |
May 13, 2016 |
9633949 |
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14218060 |
Jun 21, 2016 |
9373586 |
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13676260 |
May 20, 2014 |
8728936 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H01L
23/5329 (20130101); H01L 23/53238 (20130101); H01L
23/5283 (20130101); H01L 21/7682 (20130101); H01L
23/53228 (20130101); H01L 21/76885 (20130101); H01L
23/5384 (20130101); H01L 23/53295 (20130101); H01L
23/53257 (20130101); H01L 23/53266 (20130101); H01L
23/53233 (20130101); H01L 21/76892 (20130101); H01L
29/0649 (20130101); H01L 23/5226 (20130101); H01L
23/5386 (20130101); H01L 21/32139 (20130101); H01L
23/53214 (20130101); H01L 21/31053 (20130101); H01L
21/76852 (20130101); H01L 23/53223 (20130101); H01L
2924/0002 (20130101); H01L 23/5222 (20130101); H01L
2924/0002 (20130101); H01L 2924/00 (20130101) |
Current International
Class: |
H01L
21/00 (20060101); H01L 21/3213 (20060101); H01L
23/522 (20060101); H01L 23/532 (20060101); H01L
21/768 (20060101); H01L 23/528 (20060101); H01L
21/3105 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
Non-Final Office Action dated Jul. 18, 2013 for U.S. Appl. No.
13/676,260. cited by applicant .
Notice of Allowance dated Nov. 27, 2013 for U.S. Appl. No.
13/676,260. cited by applicant .
Non-Final Office Action dated Aug. 5, 2015 for U.S. Appl. No.
14/218,060. cited by applicant .
Final Office Action dated Dec. 4, 2015 for U.S. Appl. No.
14/218,060. cited by applicant .
Notice of Allowance dated Feb. 22, 2016 for U.S. Appl. No.
14/218,060. cited by applicant .
Non-Final Office Action dated Jul. 19, 2016 for U.S. Appl. No.
15/153,967. cited by applicant .
Notice of Allowance dated Dec. 12, 2016 for U.S. Appl. No.
15/153,967. cited by applicant.
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Primary Examiner: Patel; Reema
Attorney, Agent or Firm: Eschweiler & Potashnik, LLC
Parent Case Text
REFERENCE TO RELATED APPLICATIONS
This Application is a Continuation of U.S. application Ser. No.
15/153,967 filed on May 13, 2016, which is a Continuation of U.S.
application Ser. No. 14/218,060 filed on Mar. 18, 2014 (now U.S.
Pat. No. 9,373,586 issued on Jun. 21, 2016), which is a
Continuation-In-Part of U.S. application Ser. No. 13/676,260 filed
on Nov. 14, 2012 (now U.S. Pat. No. 8,728,936 issued on May 20,
2014). The contents of the above-referenced applications are hereby
incorporated by reference in their entirety.
Claims
What is claimed is:
1. A method for forming an interconnect structure, comprising:
forming an opening within a sacrificial layer, the sacrificial
layer being over a substrate; forming a conductive material within
the opening and over the sacrificial layer, wherein the conductive
material within the opening defines a conductive body; patterning
the conductive material to define a conductive projection extending
outward from the conductive body; removing the sacrificial layer;
and forming a dielectric material surrounding the conductive body
and the conductive projection.
2. The method of claim 1, wherein the removing of the sacrificial
layer exposes a sidewall of the conductive body.
3. The method of claim 1, wherein the sacrificial layer comprises a
homopolymer or copolymer.
4. The method of claim 1, wherein the removing of the sacrificial
layer exposes an upper surface of the substrate.
5. The method of claim 1, further comprising: depositing a hard
mask layer over the sacrificial layer; patterning the hard mask
layer to form a patterned hard mask layer; and etching the
sacrificial layer according to the patterned hard mask layer to
form the opening in the sacrificial layer.
6. The method of claim 1, further comprising: forming a patterned
photoresist layer over the conductive material; and etching the
conductive material according to the patterned photoresist layer to
define the conductive projection.
7. The method of claim 1, wherein the conductive material comprises
copper and manganese.
8. The method of claim 1, wherein the conductive projection
comprises angled sidewalls that give the conductive projection a
width that decreases as a distance from the conductive body
increases; and wherein the conductive body laterally extends past
the angled sidewalls of the conductive projection.
9. The method of claim 1, further comprising: concurrently forming
a barrier layer over the conductive body and the conductive
projection after the removing of the sacrificial layer.
10. The method of claim 9, wherein the barrier layer comprises a
self-forming barrier formed by annealing the conductive body and
the conductive projection at a temperature of greater than
approximately 200.degree. C.
11. The method of claim 9, wherein the barrier layer continuously
extends along sidewalls and upper surfaces of the conductive body
and the conductive projection.
12. A method for forming an interconnect structure, comprising:
etching one or more sacrificial materials over a substrate to
define an opening extending through the one or more sacrificial
materials; forming metal within the opening and over the one or
more sacrificial materials, wherein the metal within the opening
defines a metal body; selectively etching the metal to define a
metal projection extending from the metal body, wherein the metal
projection is set back from sidewalls of the metal body; removing
the one or more sacrificial materials to expose opposing sidewalls
of the metal body; and forming a dielectric material surrounding
the metal body and the metal projection.
13. The method of claim 12, further comprising: performing a
planarization process to remove the dielectric material from
directly over the metal projection and to expose a topmost surface
of the metal projection.
14. The method of claim 12, wherein the metal completely covers the
one or more sacrificial materials prior to the selectively etching
of the metal.
15. The method of claim 12, further comprising: removing the one or
more sacrificial materials using one or more of etching, wet
stripping, annealing, ultraviolet (UV) radiation, and infrared (IR)
radiation.
16. The method of claim 12, wherein the metal projection comprises
angled sidewalls, which cause a width of the metal projection to
decrease as a distance from the metal body increases.
17. The method of claim 12, further comprising: concurrently
forming a barrier layer over the metal body and the metal
projection after the removing of the one or more sacrificial
materials.
18. A method for forming an interconnect structure, comprising:
forming an opening within a sacrificial material over a substrate;
forming a conductive material within the opening and over the
sacrificial material; patterning the conductive material to define
upper sidewalls that protrude outward from horizontally extending
surfaces of the conductive material; removing the sacrificial
material; and forming a dielectric material around the conductive
material.
19. The method of claim 18, wherein the upper sidewalls of the
conductive material are tapered so that an upper width of the
conductive material above the horizontally extending surfaces
decreases as a distance from the substrate increases.
20. The method of claim 19, wherein the conductive material has
lower sidewalls below the horizontally extending surfaces, which
are tapered so that a lower width of the conductive material below
the horizontally extending surfaces increases as the distance from
the substrate increases.
Description
BACKGROUND
As the density of semiconductor devices increases and the size of
circuit elements becomes smaller, the resistance capacitance (RC)
delay time increasingly dominates the circuit performance. To
reduce the RC delay, there is a desire to switch from conventional
dielectrics to low-k dielectrics. These materials are particularly
useful as intermetal dielectrics, IMDs, and as interlayer
dielectrics, ILDs. However, low-k materials present problems during
processing, especially during the processing of the conductive
material used to make interconnects.
BRIEF DESCRIPTION OF THE DRAWINGS
FIGS. 1A-1M are partial cross sectional views illustrating steps of
one embodiment of forming an interconnect structure in accordance
with the disclosure.
FIG. 2 illustrates a flow diagram of some embodiments of a method
for the fabrication of an interconnect structure in accordance with
the disclosure.
DETAILED DESCRIPTION
The description herein is made with reference to the drawings,
wherein like reference numerals are generally utilized to refer to
like elements throughout, and wherein the various structures are
not necessarily drawn to scale. In the following description, for
purposes of explanation, numerous specific details are set forth in
order to facilitate understanding. It may be evident, however, to
one of ordinary skill in the art, that one or more aspects
described herein may be practiced with a lesser degree of these
specific details. In other instances, known structures and devices
are shown in block diagram form to facilitate understanding.
Semiconductor devices are manufactured or fabricated on
semiconductor wafers using a number of different processing steps
to create transistor and interconnection elements. To electrically
connect transistor terminals associated with the semiconductor
wafer, conductive (e.g., metal) wires, conductive vias, and the
like are formed in dielectric materials as part of the
semiconductor device. The conductive wires and vias couple
electrical signals and power between transistors, internal circuit
of the semiconductor devices, and circuits external to the
semiconductor device.
In forming the interconnection elements the semiconductor wafer may
undergo, for example, masking, etching, and deposition processes to
form the desired electronic circuitry of the semiconductor devices.
In particular, multiple masking and etching steps can be performed
to form a pattern of recessed areas in a dielectric layer, such as
a low-k dielectric layer, on a semiconductor wafer that serve as
trenches and via holes for the interconnections. A deposition
process may then be performed to deposit a metal layer over the
semiconductor wafer thereby depositing metal both in the trenches
and via holes and also on the non-recessed areas of the
semiconductor wafer.
Increasingly, low-k dielectric layers are used to reduce signal
delay and power loss effects as integrated circuit devices are
scaled down. One way this has been accomplished has been to
introduce porosity or dopants into the dielectric insulating
layer.
As a result, the need for lower dielectric constant materials has
resulted in the development of several different types of organic
and inorganic low-k materials. In particular, incorporation of
low-k materials with dielectric constants less than about 3.0 has
become standard practice as semiconductor feature sizes have
diminished to less than 0.13 microns. As feature sizes decrease
below 0.13 microns, for example to 65 nm and below, materials with
dielectric constants less than about 2.5 are often used. Several
different organic and inorganic low-k materials have been developed
and proposed for use in semiconductor devices as insulating
material having dielectric constants between about 2.2 and about
3.0.
Low-k dielectric materials, however, are susceptible to damage from
the etching processes because they are softer, less chemically
stable or more porous, or any combination of these factors. The
plasma damage can manifest itself in higher leakage currents, lower
breakdown voltages, and changes in the dielectric constant
associated with the low-k dielectric material.
There is, therefore, a need in the integrated circuit manufacturing
art to develop a manufacturing process whereby interconnect
structures may be formed without encountering the various problems
presented by porous low-K dielectric layers to improve integrated
circuit device yield, performance, and reliability.
Accordingly, the present disclosure is directed to methods of
fabrication of an interconnect structure. The methods provide a
process for defining an interconnect structure that eliminates
low-k dielectric damage caused during etching processes. The
process provides the further advantage of removing etch stop or
NFARC (nitrogen-free anti-reflective coating) layers, making the
process more cost effective.
FIGS. 1A-1M illustrate a plurality of partial cross section
diagrams illustrating one embodiment of a method of forming an
interconnect structure at stages in the manufacturing process
according to the disclosure. Referring to FIG. 1A, a semiconductor
substrate 102 having a conductive region 103 is provided. Substrate
102 is understood to include a semiconductor wafer or substrate,
comprised of a semiconducting material such as silicon or
germanium, or a silicon on insulator structure (SOI). Semiconductor
structure can further include one or more conductive layers (such
as metal or silicon) and/or insulating layers, and one or more
active or passive devices formed in or over the substrate, or the
like, for example, a display substrate such as a liquid crystal
display (LCD), plasma display, electro-luminescence (EL) lamp
display, or a light emitting diode (LED) substrate.
Overlying substrate 102 and covering conductive region 103 is a
sacrificial layer 104. Sacrificial layer 104 comprises a
homopolymer or copolymer. In one embodiment, sacrificial layer 104
comprises one or more of polyimide or P(neopentyl
methacrylate-co-theylene glycol dimethacrylate copolymer
(P(npMAco-EGDA). Sacrificial layer 104 is deposited by one or more
of chemical vapor deposition (CVD) or spin-on coating processes.
The thickness of the sacrificial layer will be in a range of from
about 10000 .ANG. (angstroms) to about 100 .ANG..
A dielectric hard mask layer 108 is then deposited 106 by, for
example, a CVD process, as illustrated in FIG. 1B. The dielectric
hard mask layer 108 is used to pattern the sacrificial layer 104 in
a subsequent photolithographic process. In some embodiments, the
dielectric hard mask layer 108 comprises a material such as
silicon-oxide, silicon-nitride, silicon-oxynitride, and
silicon-carbide. The dielectric hard mask layer 108 will have a
thickness of from about 1000 .ANG. to about 10 .ANG..
Following deposition of the hard mask layer 108, in one embodiment,
a photoresist film 112 is formed by process 110 over the hard mask
layer 108, as illustrated in FIG. 1C. Conventional photoresist
materials may be used. The photoresist film 112 can be a
carbon-containing, organic material. Various photoresists having
various thicknesses can be utilized. Photo resist patterning and
etching 114 are performed in FIG. 1D
Hard mask 108 patterning and first etching process 116 through the
hard mask layer 108 and into the sacrificial layer 104 are then
performed to remove a portion of sacrificial layer 104 and form a
first feature defined by an opening 118 in the sacrificial layer
104, as shown in FIG. 1E. In one embodiment, first feature
comprises a trench.
In FIG. 1F, a metal layer 124 is deposited 122 over first feature
and filling opening 118 in sacrificial layer 104 to form a metal
body 125 therein. Metal body 125 is defined by a lower portion
124(a) of the metal layer 124. Metal body 125 includes angled
opposing sidewalls. In some embodiments, the metal body 125
comprises a metal wire layer configured to provide for a lateral
interconnection (i.e., an interconnection parallel to the surface
of the semiconductor substrate 102). In one embodiment, the metal
layer 124 can be formed from elements such as aluminum (Al),
tungsten (W), copper (Cu), copper manganese (CuMn), copper-titanium
(CuTi), copper vanadium (CuV), copper chromium (CuCr), or
copper-niobium (CuNb), and the like. Metal layer 124 can be formed
using, for example, a plasma vapor deposition technique, among
others. Metal layer 124 can be deposited at a thickness, in one
embodiment, of from about 100 .ANG. (Angstroms) to about 20,000
.ANG..
A photoresist film 112' is formed over the metal layer 124 and
patterned 126 by conventional techniques, as shown in FIG. 1G. A
second etch 128 is performed to pattern and etch an upper portion
124(b) of the metal layer 124 to form a second feature having first
recesses 123(a), 123(b) and defined by a vertical projection 127
extending from the metal body 125, as illustrated in FIG. 1H.
The vertical projection 127 includes angled opposing sidewalls,
129(a) and 129(b), and upper surface 130. In some embodiments, the
angled opposing sidewalls, 129(a) and 129(b), are tapered such that
the vertical projection 127 has a narrower top surface 127(a) and
wider bottom surface 127(b) (i.e., w.sub.1<w.sub.2). In some
embodiments, the vertical projection 127 comprises a metal via
configured to provide for a vertical interconnection between an
underlying metal body and an overlying metal body.
In FIG. 1I, sacrificial layer 104 is removed by one or more of, for
example, etching, wet stripping, annealing, UV or IR radiation
techniques (not shown). Removal of the sacrificial layer 104
exposes angled opposing sidewalls 132(a), 132(b) of metal body 125
and forms second recesses 131(a), 131(b). Angled opposing sidewalls
132(a), 132(b) taper such that metal body 125 has a wider top
surface 125(a) and narrower bottom surface 125(b).
In one embodiment, a barrier layer 134 is formed overlying and
encompassing metal body 125 and vertical projection 127 and
disposed between dielectric material 136 (FIG. 1K) and metal layer
124. By encompassing metal body 125 and vertical projection 127,
barrier layer 134 is continuous. Barrier layer 134 is formed by
depositing a dielectric material, for example, silicon-nitride and
silicon-carbide. In one embodiment, barrier layer 134 is formed by
depositing a metal, for example, TiN, TaN, Co, WN, TiSiN, TaSiN, or
combinations thereof. In another embodiment, an annealing 135 is
performed at a temperature of about greater than 200.degree. C.,
such that barrier layer 134 is self-forming, as illustrated FIG.
1J. The thickness of the barrier layer 134 can be, in one
embodiment, from about 1 .ANG. (Angstrom) to about 300 .ANG..
In FIG. 1K, low-k dielectric material 136 is deposited by process
137 to fill first 123(a), 123(b) and second 131(a), 131(b) recesses
and overlying the upper surface 130 of the vertical projection 127
to form a dielectric region 136'. Low-k dielectric material 136
thus encapsulates vertical projection 127 and metal body 125. The
low-k dielectric includes dielectrics with k less than about 3.
Such dielectrics include, for example, carbon-doped silicon
dioxide, also referred to as organosilicate glass (OSG) and
carbon-oxide. Low-k materials may also include borophosphosilicate
glass (BPSG), boro silicate glass (BSG), and phosphosilicate glass
(PSG), among others. The dielectric layer 136 may be formed using,
for example, tetraethyl orthosilicate (TEOS), chemical vapor
deposition (CVD), plasma enhanced CVD (PECVD), low pressure CVD
(LPCVD), or spin-on coating techniques. The thickness of the low-k
dielectric will be, in one embodiment, from about 100 .ANG. to
about 20000 .ANG..
In the embodiment illustrated in FIG. 1K, at least one air gap 138
is formed within the dielectric material 136. The air gap 138 is
disposed in the dielectric region 136' between angled sidewalls
132(a), 132(b) of adjacent metal bodies 125. Air gap 138 can be
self-forming during deposition of the low-k material 136. In one
embodiment, the size of the air gap can be from about 0 .ANG. to
about 20000 .ANG.. It is contemplated, however, that the size of
the air gap can be controlled by the low-k material 136 deposition
process. A chemical mechanical polishing (CMP) process can then be
performed to remove excess dielectric layer 136 and expose upper
surface 130 of vertical projection 127, as illustrated in FIG.
1L.
Following CMP process, the method can be repeated to form an
additional metal layer 150 of an interconnect structure 152
overlying vertical projection 127 and electrically coupled to the
vertical projection 127, as illustrated in FIG. 1M, so as to form
an integrated circuit of at least two adjacent interconnect
structures, 148 and 152.
FIG. 2 illustrates a flow diagram of some embodiments of a method
200 for formation of a semiconductor structure according to an
embodiment of the present disclosure. While method 200 is
illustrated and described below as a series of acts or events, it
will be appreciated that the illustrated ordering of such acts or
events are not to be interpreted in a limiting sense. For example,
some acts may occur in different orders and/or concurrently with
other acts or events apart from those illustrated and/or described
herein. In addition, not all illustrated acts may be required to
implement one or more aspects or embodiments of the description
herein. Further, one or more of the acts depicted herein may be
carried out in one or more separate acts and/or phases.
At step 202 a semiconductor substrate is provided. A sacrificial
layer is then formed over the substrate at step 204.
At step 206, a hard mask layer is deposited overlying the
sacrificial layer.
At step 208, a first feature is formed by patterning and etching
through hard mask and sacrificial layer to form an opening in the
sacrificial layer.
At step 210, a metal layer is deposited overlying first feature and
filling the feature opening.
At step 212, an upper portion of the metal layer is patterned and
etched to form a second feature.
At step 214, sacrificial layer is removed.
At step 216, a barrier layer is formed by CVD, PVD, MOCVD or ALD,
or barrier layer can be self-formed by annealing.
At step 218, a low-k dielectric material is deposited to fill
recesses and encompass metal body and vertical projection.
At step 220, at least one air gap is formed in the low-k dielectric
material. The air gap is disposed in the dielectric region between
adjacent interconnect structures.
At step 222, a CMP process is performed to remove excess dielectric
layer and expose a top surface of the vertical projection. The
method then ends.
It will be appreciated that equivalent alterations and/or
modifications may occur to one of ordinary skill in the art based
upon a reading and/or understanding of the specification and
annexed drawings. The disclosure herein includes all such
modifications and alterations and is generally not intended to be
limited thereby. In addition, while a particular feature or aspect
may have been disclosed with respect to only one of several
implementations, such feature or aspect may be combined with one or
more other features and/or aspects of other implementations as may
be desired. Furthermore, to the extent that the terms "includes",
"having", "has", "with", and/or variants thereof are used herein,
such terms are intended to be inclusive in meaning--like
"comprising." Also, "exemplary" is merely meant to mean an example,
rather than the best. It is also to be appreciated that features,
layers and/or elements depicted herein are illustrated with
particular dimensions and/or orientations relative to one another
for purposes of simplicity and ease of understanding, and that the
actual dimensions and/or orientations may differ substantially from
that illustrated herein.
Therefore, the disclosure relates to method for forming a
conductive interconnect structure, and a related apparatus.
In some embodiments, the present disclosure relates to a method for
forming an interconnect structure. The method comprises forming an
opening within a sacrificial layer that is over a substrate, and
forming a conductive material within the opening and over the
sacrificial layer. The conductive material within the opening
defines a conductive body. The method further comprises patterning
the conductive material to define a conductive projection extending
outward from the conductive body, and removing the sacrificial
layer. The method further comprises forming a dielectric material
surrounding the conductive body and the conductive projection.
In other embodiments, the present disclosure relates to a method
for forming an interconnect structure. The method comprises etching
one or more sacrificial materials over a substrate to define an
opening extending through the one or more sacrificial materials.
The method further comprises forming metal within the opening and
over the one or more sacrificial materials. The metal within the
opening defines a metal body. The method further comprises
selectively etching the metal to define a metal projection
extending from the metal body. The metal projection is set back
from sidewalls of the metal body. The method further comprises
removing the one or more sacrificial materials to expose opposing
sidewalls of the metal body, and forming a dielectric material
surrounding the metal body and the metal projection.
In yet other embodiments, the present disclosure relates to an
integrated chip. The integrated chip comprises a copper body over a
substrate, and a copper projection disposed on and in contact with
the copper body. The copper projection has angled sidewalls that
cause a width of the copper projection to decrease as a distance
from the copper body increases. The copper body laterally extends
past the angled sidewalls of the copper projection.
* * * * *